Ultrasound as an independent screening tool for diagnosing cancers, particularly in breast tissue, is becoming more widely recognized and accepted within the medical community. Historically, in the context of breast exams and breast cancers, ultrasound was first used to diagnose breast cancers if the location of the abnormality is first discovered by another modality, such as mammography or physical examination. Recently, ultrasound as a stand-alone diagnostic tool for breast cancers has become more widely accepted based on the development of technology that enables ultrasound to be used to screen the entire breast tissue and have an acceptably high success rate in finding abnormalities that may be cancerous. One system that has been developed to uniformly and reliably screen tissues, such as breast tissue, for cancer uses ultrasound probes to create a contiguous and complete set of scan images for the entire area of the tissue being screened. One such system is described in U.S. Pat. No. 6,524,246, the disclosure of which is incorporated herein by reference in its entirety.
One of the limitations of such a system is the amount of time needed to perform the scans. Even though such a system may automate the acquisition of ultrasound images, the process can still be somewhat slow, especially when compared to other breast tissue screening methods, such as mammography. Another limitation with present ultrasound systems is that they all rely on the ultrasound probe coming into contact with the surface of the tissue being screened. This contact causes deformation of the tissue, and deformation of the tissue can cause difficulties for identifying abnormalities when the ultrasound images are being viewed.